We evaluated each method using the source-to-distortion ratio (SDR) [1]}
of the directional target speech, which measures the separation quality and the absence of distortion.
For each of the methods, the SDR behaviors with respect to the elapsed time are shown in Fig. REF .
Note that all methods except for FastMNMF are initialized using ILRMA.
Multichannel Wiener filtering using ILRMA estimates improves the SDR value to some extent,
and FastMNMF or rank-constrained SCM estimation further improves the separation quality.
From Fig. REF , we can confirm that
the second-stage acceleration achieves the fastest and most efficient target speech extraction.
